1. Field of the Invention
The present invention relates to a method of storing a silver halide photographic emulsion, silver halide photographic emulsion, and a silver halide light-sensitive material, and more specifically to a storing method which can lower the deterioration of performance during the storage after preparation of a silver halide photographic emulsion having a high sensitivity and an excellent graininess.
2. Description of the Related Art
A silver halide photographic emulsion is prepared through steps including formation of grains, desalting, and chemical sensitization. If necessary, an additive, a coupler dispersion or the like is added to the silver halide emulsion after preparation thereof. The emulsion is applied on a support, and dried. The obtained material is cut into pieces each having a predetermined size, and packaged.
After the preparation of the silver halide photographic light-sensitive emulsion, the emulsion may be coated on a substrate immediately, or, if necessary, the emulsion prepared may be stored for a certain period of time in the state of sol or gel before application. Due to the restrictions placed on the preparing apparatus and method, the emulsion is usually stored for a certain period of time after preparation.
During the storage, photographic properties or performances (for example, sensitivity and fogging) are likely to change. The change of the properties should be suppressed to as small a level as possible. For this reason, it is generally considered that a prepared silver halide photographic emulsion should be stored at a low temperature of, for example, 5.degree. C. so as to suppress the change with time as effectively as possible.
Researches has been conducted for suppressing the change with time. For example, Research Disclosures Nos. 10152 and 13941 disclose a method of storing a silver halide photographic emulsion in a freeze-dried state. However, such a method involves a severe restriction in terms of production facilities, and has the drawback in which fogging increases at the moment of freeze-drying with a high-sensitivity emulsion.
British Patent 1,159,385 and JP-A-1-287672 disclose a method of improving the storage stability by storing an emulsion in a deoxygenated state created by nitrogen substitution. Although such a method is certainly effective and useful, the method involves a severe restriction in production facilities, and a drawback of its effect being insufficient, probably due to the fact that it is substantially impossible to completely shut off oxygen. Therefore, there has been a demand for improvement of the method.